Seeking fix for corn fungus

I have tried growing sweet corn for the first time this year. I have noticed that some of the ears have misshapen kernels with what appears to be a black growth. What is this and what should I do?

-- Lisa Jenkins, Barrington

It sounds like you are seeing corn smut, which is a fairly common disease on sweet corn. It is caused by a fungus that can infect various parts of the corn plant, including stalks, ears, leaves and tassels.

When the fungus infects the developing kernels in an ear of corn, it can lead to the formation of galls that can grow quite large. These galls, sometimes 4 to 5 inches wide, typically have a silvery gray outer coating and look like super-sized corn kernels. Inside is a mass of black fungus. As a gall matures, its outer layer dries and cracks open to release powdery black spores that are spread by wind and splashing rain.

The hot dry summer weather this year has been conducive to the growth of this fungus. When the soil is dry, dust can blow around more readily and carry the fungus spores from one area to another. The unusually high temperatures have given the spores good conditions to germinate, although they also must have water that collects in the silk, leaf blades and other parts of the corn.

There is not much you can do about this problem other than cut out the galls. Since the spores are spread by wind, all corn growers in the surrounding area would need to go through their corn plants two to three times during the season to cut out any smut balls before they break open and release the spores. The galls should be destroyed by burning or burying and not put in the compost heap.

If these measures were taken, it still would require two to three years to reduce the corn smut. Crop rotation away from corn can also help.

There is some degree of tolerance to corn smut among some of the newer corn varieties, including 'Apache,' 'Aztec,' 'Comanche,' 'Sweet Sue,' 'Bellringer,' 'Golden Security,' 'Merit,' 'Calumet,' 'Capitan,' 'Golden Gleam,' 'Wintergreen,' 'Midway,' 'Pacer,' 'Bravo' and 'Gold Cup.' But in a hot summer such as this one, which provides favorable conditions for the spores to germinate, any variety can get corn smut. You may or may not get corn smut next year.

The immature, tender smut gall is edible and is sometimes called "maize mushroom." It is highly prized by cooks in Mexico, who use it in soups, sauces, quesadillas and other dishes. Harvest the fungus galls when they have expanded, but before the outer layer becomes black and dried out.